0:00:10.959,0:00:13.877
Light, where does light come from?

0:00:14.083,0:00:16.175
All the light around us,

0:00:16.175,0:00:19.642
even the one coming from[br]these lit objects

0:00:19.643,0:00:20.631
comes from the sky.

0:00:20.632,0:00:24.290
One way or another it reached us,[br]maybe some time ago, from the sky.

0:00:24.576,0:00:27.197
Light comes from cosmos only.

0:00:28.248,0:00:30.648
From which cosmos? From the one around us.

0:00:30.778,0:00:34.798
From this sky, that we cannot see[br]in our city.

0:00:35.501,0:00:39.168
Bergamo cannot see this sky,[br]you can see this sky in Africa only.

0:00:39.848,0:00:44.567
You see it in the dark, when the city[br]doesn't illuminate night sky.

0:00:45.157,0:00:48.137
If you happen to go in southern world,[br]you can see this sky.

0:00:48.138,0:00:51.321
Well, let's imagine to be some time ago,

0:00:51.322,0:00:53.615
two and half million years ago.

0:00:54.042,0:00:59.084
There will even been a first hominid[br]in his evolution phase

0:00:59.937,0:01:01.537
who raised up from the ground

0:01:02.205,0:01:05.940
and he realized what he got[br]above his head.

0:01:06.260,0:01:10.171
Imagine that moment,[br]an important moment for our history

0:01:10.770,0:01:13.450
that comes from the remote ancient times.

0:01:14.391,0:01:20.489
From that moment onwards, man always had[br]with him in his culture

0:01:20.490,0:01:26.231
the awareness of universe[br]and of light coming from the sky.

0:01:26.721,0:01:28.074
Let's have a quantum leap.

0:01:28.075,0:01:30.814
You know this profile very well.

0:01:30.815,0:01:34.041
It's Stonehenge profile.[br]What Stonehenge is?

0:01:34.261,0:01:37.440
It is an achievement[br]of a primitive people.

0:01:37.441,0:01:40.449
About 4,500 years ago,

0:01:40.450,0:01:43.139
then practically before History begins.

0:01:43.140,0:01:47.250
It is an example on how the study,[br]the sky observation,

0:01:47.253,0:01:50.582
had shaped the human culture.

0:01:50.941,0:01:55.691
In order to make this particular[br]building system,

0:01:56.031,0:01:59.511
that ancient people did a huge effort,

0:01:59.512,0:02:02.900
they brought very heavy stones

0:02:02.901,0:02:07.248
from dozens, perhaps hundreds[br]kilometers far away,

0:02:07.249,0:02:10.549
to structure them[br]in a very large circular frame.

0:02:10.888,0:02:12.328
Why?

0:02:12.329,0:02:14.738
In order to watch stars.

0:02:14.739,0:02:17.669
To see planet motion,[br]to understand when it is sow time,

0:02:17.670,0:02:19.002
when to harvest.

0:02:19.003,0:02:22.371
In order to do rituals[br]related to mythologies,

0:02:22.372,0:02:26.290
just related to information[br]coming from the sky.

0:02:26.291,0:02:28.873
Sky always shaped our culture:

0:02:28.874,0:02:32.171
Mayan, Egyptian and[br]all the humanity history

0:02:32.172,0:02:36.113
and, according to this example,[br]using technology,

0:02:36.831,0:02:39.221
most advanced features at that age.

0:02:39.482,0:02:42.742
Let's have another jump,[br]about 2,300 years.

0:02:43.339,0:02:45.468
We are in the Mediterranean Sea,

0:02:45.469,0:02:48.572
a Greek-Roman ship[br]carries some goods

0:02:48.584,0:02:51.667
between Greece and Italy

0:02:51.959,0:02:58.042
and it sinks in front of Kythera Island,[br]a Peloponnese island.

0:02:58.214,0:03:02.093
In 1906, at previous century beginning,[br]this wreck was found

0:03:03.013,0:03:06.611
and while collecting the wreck stuff,

0:03:06.612,0:03:10.361
in the hold of a 2,200 years old ship

0:03:10.362,0:03:12.921
at that point,[br]apart from the usual amphorae,

0:03:12.922,0:03:16.632
structures like these were found,[br]some sort of small wheels

0:03:17.214,0:03:22.451
completely covered with limestone,[br]brought to Athens museum

0:03:22.452,0:03:25.978
and left there for 60 years long.[br]Nobody knows what they were.

0:03:26.459,0:03:29.164
60 years later, they make them[br]radio-graphs with x-ray

0:03:29.165,0:03:32.600
and discover within those wheels[br]some very thin gears

0:03:33.209,0:03:37.168
like clocks of 1600 century,[br]but we are in 200 b.C. century.

0:03:37.182,0:03:38.800
This was some sort of astrolabe,

0:03:38.808,0:03:42.875
a system which allowed[br]to powerful people of that time

0:03:42.876,0:03:47.502
to compute planet motion,[br]above all sun and moon eclipses.

0:03:47.514,0:03:52.028
Imagine what does it mean[br]for a General, or for a politician,

0:03:52.029,0:03:56.700
to know when the sun is going to hide,[br]when the moon is going to be overshadowed.

0:03:57.358,0:03:59.881
An incredibly sophisticated technology.

0:04:00.417,0:04:03.043
Marcus T. Cicero told us that[br]two of this machine type,

0:04:03.050,0:04:08.347
were available at that time,[br]in the Greek-Roman civilization.

0:04:08.348,0:04:11.790
We found one of them undersea,[br]an extraordinary good luck!

0:04:11.792,0:04:15.126
Another example of how technology,[br]the more advanced one,

0:04:15.127,0:04:16.899
had been made available,

0:04:16.899,0:04:17.683
but for what?

0:04:17.684,0:04:19.966
In order to study, to understand the sky.

0:04:21.221,0:04:22.472
Let's have another jump.

0:04:22.473,0:04:24.791
This is an Almagesto page.

0:04:24.792,0:04:28.792
Almagesto was a sort of encyclopedia,[br]like the Britannica one,

0:04:28.811,0:04:31.491
where all the information known[br]to mankind were collected

0:04:32.349,0:04:36.141
in one thousand years between[br]the end of Roman Empire

0:04:36.781,0:04:38.841
and half of first millennium.

0:04:39.678,0:04:43.408
As you can see from these images,[br]Earth is perfectly shaped.

0:04:44.102,0:04:49.342
It has all its continents: North and[br]South America, even Australia.

0:04:49.662,0:04:52.766
What's the problem?[br]It is at the center of the world.

0:04:52.767,0:04:55.314
All the celestial spheres surround it.

0:04:55.808,0:04:58.591
The one carrying the Sun,[br]the one carrying the Moon,

0:04:58.592,0:05:02.739
the various planets, gradually up to[br]the sphere that leads to the fixed stars.

0:05:03.125,0:05:09.250
Indeed, being in 1550, America[br]was discovered by Columbus in 1492,

0:05:09.652,0:05:13.643
but it is not yet a clear understanding[br]where this planet stands

0:05:13.644,0:05:14.962
within the Universe.

0:05:14.963,0:05:18.301
Indeed, we have to wait until 1609,[br]when Galileo,

0:05:18.302,0:05:23.062
using this small spyglass which[br]you can buy with 50€ in a general store,

0:05:23.432,0:05:28.272
understood that some satellites[br]were turning around a planet, Jupiter,

0:05:28.603,0:05:31.082
and that they were drilling, ruining,

0:05:31.083,0:05:34.834
they were destroying[br]celestial spheres harmony.

0:05:34.845,0:05:37.724
At the end Earth found[br]its position in the Universe.

0:05:38.163,0:05:40.372
The Sun was not turning around the Earth,

0:05:40.373,0:05:42.132
but Earth was turning around Sun.

0:05:42.812,0:05:45.423
Spyglass, the technology of that moment,

0:05:45.445,0:05:51.413
now, the technological development[br]leads to extraordinary progresses.

0:05:51.675,0:05:53.963
This is a previous century spyglass,

0:05:53.964,0:05:59.959
it is the spyglass through which Hubble[br]looked at our galaxy for a long time,

0:06:00.469,0:06:03.013
he took pictures of our set of Stars,

0:06:03.459,0:06:06.251
that then it was thought to be[br]the whole Universe

0:06:06.631,0:06:11.420
and while studying some small stars,[br]a bit blurry,

0:06:11.842,0:06:15.281
from night to night he understood[br]that other galaxies exist,

0:06:15.282,0:06:16.410
very, very far away.

0:06:16.977,0:06:20.145
From night to night[br]Universe expanded

0:06:20.146,0:06:22.027
by a factor of a thousand more

0:06:22.028,0:06:24.693
and from then on[br]we continued expanding it,

0:06:24.975,0:06:28.552
up to, pretty much, to its origins.

0:06:28.553,0:06:32.673
This by using a telescope clearly[br]very much powerful than Galileo's one.

0:06:32.930,0:06:35.684
Today we have in space[br]the telescope of telescopes:

0:06:36.344,0:06:39.983
Hubble telescope,[br]which looks at the Universe

0:06:40.523,0:06:44.392
using extraordinarily favorable conditions

0:06:44.393,0:06:46.536
being able to do observations[br]from the space

0:06:46.537,0:06:48.843
and this picture you can see[br]on the right side

0:06:48.844,0:06:52.701
is a Cosmos pinhead[br]on our head above

0:06:52.702,0:06:56.764
hugely magnified by Hubble

0:06:57.042,0:07:00.417
and we can see early galaxies,[br]early protostars,

0:07:00.422,0:07:04.083
we can see an Universe how it was[br]billions and billions of years ago.

0:07:05.617,0:07:09.302
I told you that technology is fundamental[br]to understand the Universe around us

0:07:09.889,0:07:12.092
but you'll see how amazing[br]is the pace

0:07:12.093,0:07:15.484
of technology evolution[br]in the last century.

0:07:16.334,0:07:20.738
Last century allowed us to do much greater[br]advancements

0:07:20.739,0:07:24.340
than in thousands and billions of years[br]before now.

0:07:24.751,0:07:27.834
You can see this picture,[br]we are in Scrovegni Chapel

0:07:28.365,0:07:36.413
and we see how in 1301 Giotto[br]painted a wonderful series of paintings

0:07:36.851,0:07:40.253
including the Nativity and you can value[br]this painting beauty

0:07:40.254,0:07:47.167
because we can see the shape,[br]the persons images,

0:07:47.168,0:07:50.181
animals, a hut perspective

0:07:50.182,0:07:54.735
but above the hut we see a ugly comet

0:07:55.124,0:07:58.344
some sort of reddish shapeless small ball

0:07:58.345,0:08:01.327
and we wonder why a so great painter[br]as Giotto was

0:08:01.729,0:08:04.942
had drawn a so ugly comet.

0:08:04.943,0:08:08.153
Because he had seen it in the sky,[br]because in that moment he saw

0:08:08.154,0:08:10.932
that star passing on his head.

0:08:10.933,0:08:13.343
It is Halley comet, which passes[br]each 76 years

0:08:13.620,0:08:17.239
and in 1301 it was passing[br]on this painter's head

0:08:17.240,0:08:18.939
who precisely copied it.

0:08:18.940,0:08:23.202
In fact, these photo in 1910,[br]first ones of this comet,

0:08:23.203,0:08:25.424
show us a structure totally similar

0:08:25.425,0:08:27.806
to the painted one by Giotto in 1300.

0:08:28.466,0:08:32.549
In 1986, 76 years later,

0:08:32.549,0:08:35.302
man was able to make[br]his artificial satellites

0:08:35.982,0:08:38.313
his remote-controlled robots

0:08:38.759,0:08:43.109
which literally went to pinch the tail[br]of Giotto comet

0:08:43.110,0:08:44.649
In order to see how it is made.

0:08:45.080,0:08:47.776
600 years to go from eye to photography,

0:08:48.170,0:08:50.760
76 years to pass from photography

0:08:50.767,0:08:55.629
to the ability to reach Halley comet.

0:08:56.632,0:08:58.999
Technology, technology.

0:08:59.000,0:09:01.000
These gentlemen are Penzias and Wilson,

0:09:01.001,0:09:02.870
two engineers who become famous

0:09:02.871,0:09:06.162
because substantially they authored[br]a paper which says:

0:09:06.671,0:09:09.819
we tried to build an electronic equipment

0:09:09.820,0:09:11.799
with a very low environmental noise

0:09:11.800,0:09:15.361
which had practically to measure[br]no one of any noise types

0:09:15.461,0:09:18.269
and we hear a continuous, deafening noise,

0:09:18.270,0:09:20.577
coming everywhere from the universe.

0:09:20.578,0:09:22.062
This equipment has its own ear,

0:09:22.063,0:09:24.512
which is an antenna, a sort of[br]a big radio antenna,

0:09:24.513,0:09:28.073
which allowed them to realize that[br]their noise comes from everywhere.

0:09:28.094,0:09:31.896
They don't know what they had found,[br]published this finding

0:09:32.096,0:09:35.373
and after a few later,[br]others understood

0:09:35.495,0:09:38.255
that they were listening to[br]the Big Bang echo

0:09:38.256,0:09:40.234
and they awarded Nobel prize for that.

0:09:40.235,0:09:43.465
A noise which is actually the echo[br]of the initial big explosion.

0:09:44.565,0:09:48.141
Today, we perform studies of the same kind[br]using more powerful equipments.

0:09:48.723,0:09:53.410
This stratospheric balloon studied[br]that Big Bang echo,

0:09:53.803,0:09:56.755
understanding that it has[br]a very particular structure.

0:09:57.075,0:09:59.625
If you wear glasses in order to see[br]the Big Bang

0:10:00.084,0:10:03.163
they are a sort of someway[br]special Goggle glasses,

0:10:03.164,0:10:05.462
made by scientists studying these things

0:10:05.463,0:10:08.183
and you get out to see the sky,[br]you'll see a pocked one,

0:10:08.184,0:10:09.467
as it had measles.

0:10:09.468,0:10:14.861
That measles is the detail[br]of Big Bang explosion,

0:10:14.862,0:10:17.031
as you can see it 300,000 years later.

0:10:17.267,0:10:21.115
Maybe you have seen[br]a picture like this

0:10:21.116,0:10:23.484
In the headlines of main newspapers:

0:10:23.485,0:10:25.881
a satellite named Plank

0:10:25.882,0:10:29.861
completed this picture of the sky[br]affected by measles,

0:10:29.862,0:10:31.432
Big Bang measles,

0:10:31.626,0:10:36.035
this is just a sky, which revealed[br]280,000 years,

0:10:36.036,0:10:37.801
300,000 years after Big Bang.

0:10:38.337,0:10:41.490
But recently you read on newspapers[br]this unbelievable thing,

0:10:42.196,0:10:45.566
an equipment located at South Pole[br]did much more.

0:10:46.217,0:10:49.119
It found in this picture[br]of 300,000 years ago

0:10:49.697,0:10:52.406
a mark of something that happened

0:10:52.407,0:10:56.287
1 billionth of second after[br]the initial explosion.

0:10:56.288,0:10:58.918
These polarized light circles in the sky

0:10:59.296,0:11:03.867
are telling us what happened[br]just at the beginning of time.

0:11:05.390,0:11:10.494
Technology. But what happened[br]over the past 50 years?

0:11:10.495,0:11:11.945
A very big revolution.

0:11:11.946,0:11:15.063
We learned how to see the Universe colours

0:11:15.064,0:11:18.214
which are not visible to human eyes

0:11:19.496,0:11:21.607
and above all not visible from the Earth.

0:11:22.808,0:11:26.727
The Universe seen by Galileo, Hubble,[br]using telescopes,

0:11:27.248,0:11:29.815
is sending us the light[br]which goes through atmosphere.

0:11:29.816,0:11:33.445
This light is a visible light which[br]goes fairly through the air.

0:11:33.792,0:11:38.737
Radio waves seen by Penzias and Wilson[br]are like the ones done by cellular phones,

0:11:38.738,0:11:40.393
they fairly go through the air.

0:11:40.918,0:11:42.710
But there are many other waves

0:11:42.718,0:11:45.234
that cannot go through the air,

0:11:45.235,0:11:50.424
and, in order to see them, we have[br]to go out, literally, from the atmosphere.

0:11:50.852,0:11:55.169
Over the past 50 years we were able[br]to do so systematically

0:11:55.542,0:11:59.251
and we were able to get all the colors[br]of an otherwise invisible Universe.

0:12:00.296,0:12:03.808
For instance this picture you can see[br]if we shift to visible light

0:12:04.542,0:12:06.460
is the Universe, Milky Way,

0:12:06.584,0:12:10.502
which dominates our viewpoint, [br]seen from the Earth,

0:12:11.042,0:12:15.751
by the first hominids' eyes,[br]by Galileo's eyes and Hubble's ones.

0:12:15.755,0:12:16.774
in the visible range.

0:12:16.792,0:12:17.875
It has some structure,

0:12:17.876,0:12:20.164
We cannot see it clearly as a whole,

0:12:20.165,0:12:21.753
but it has these features.

0:12:21.993,0:12:23.924
If we shift in the infrared range,

0:12:24.031,0:12:26.949
which is a frequency that doesn't go[br]through the atmosphere,

0:12:27.268,0:12:29.939
we can see a totally different shape.

0:12:30.125,0:12:31.667
In the microwaves range,

0:12:31.668,0:12:34.667
the ones of the microwaves oven[br]we have in our kitchen,

0:12:34.668,0:12:36.583
again it changes completely.

0:12:36.584,0:12:40.244
In the radiowaves range, the one[br]we can see from Earth, too,

0:12:40.245,0:12:43.480
where are Penzias and Wilson measures,[br]it changes again;

0:12:43.828,0:12:46.167
some set of cold gas

0:12:46.168,0:12:49.174
which appear and give out[br]that kind of radio light.

0:12:49.364,0:12:50.793
In the ultraviolet range,

0:12:51.083,0:12:55.001
which is a color not going easily[br]through atmosphere,

0:12:55.138,0:12:59.554
all a series of stars appear which are[br]otherwise invisible in the visible range.

0:12:59.700,0:13:02.779
In the x-rays range,[br]our Universe changes again,

0:13:02.989,0:13:05.868
it looks completely different[br]with very hot sources.

0:13:06.062,0:13:09.408
To finish in the gamma rays range,[br]which are those nuclear explosions,

0:13:09.518,0:13:13.718
where some objects are exploding[br]in a nuclear way

0:13:13.719,0:13:17.608
inexhaustibly, since millions[br]and millions years.

0:13:18.250,0:13:21.917
This is the Universe we have[br]in front of our eyes

0:13:22.139,0:13:26.284
a Universe full of colours,[br]that 50 years ago we don't know.

0:13:26.660,0:13:30.794
This is the part of an invisible Universe[br]which has become a visible one,

0:13:30.795,0:13:33.857
which has unveiled during[br]the last 50 years,

0:13:34.042,0:13:36.376
thanks to people work[br]like Riccardo Giacconi,

0:13:36.426,0:13:39.313
an Italian who awarded Nobel prize in 2002

0:13:39.501,0:13:42.419
because he found Universe[br]made of X-ray sources,

0:13:42.638,0:13:45.227
nobody believed it,[br]"He can't do this experiment."

0:13:45.417,0:13:47.917
He stubbornly insisted,[br]he went to America

0:13:48.167,0:13:50.217
and he made this satellite,[br]put into orbit

0:13:50.629,0:13:52.910
and he saw first X-rays sources.

0:13:53.288,0:13:55.940
Or this satellite called Fermi,

0:13:56.170,0:13:59.869
as a tribute to our great physicist[br]in 40-50 years,

0:14:00.559,0:14:03.961
which literally observes[br]the very hot Universe

0:14:04.542,0:14:07.542
along an endless nuclear explosion.

0:14:07.792,0:14:11.418
Or these even more modern equipments[br]called "Cherenkov-light" tools

0:14:12.100,0:14:15.730
which look at light[br]with a so ultimate color

0:14:16.341,0:14:19.140
that we aren't able even[br]to produce it in our labs

0:14:20.190,0:14:22.950
a terribly high energy

0:14:23.300,0:14:27.482
produced in some cases[br]by those sources, energy monsters,

0:14:28.429,0:14:31.539
which are somewhere In our Universe.

0:14:31.869,0:14:36.092
This partially explains because[br]we have so many satellites,

0:14:36.572,0:14:39.980
each is an eye looking at[br]different colours

0:14:40.340,0:14:44.020
looking at different distances,[br]looking at a short or long distance

0:14:44.630,0:14:49.211
reaching visible Universe borders,[br]unto Big Bang touching.

0:14:50.667,0:14:54.042
Then we now have these beautiful pictures

0:14:54.171,0:14:58.617
of the Milky Way, but of the Universe, too[br]in all the imaginable colours.

0:14:59.081,0:15:03.771
This is our Universe,[br]become visible over the past 60 years,

0:15:03.977,0:15:08.311
previously its 90%[br]was completely unreachable.

0:15:08.771,0:15:12.771
We finished, did we reach[br]science fulfillment?

0:15:13.291,0:15:15.113
Do we get visible limits?

0:15:15.199,0:15:17.219
No, we don't.

0:15:17.459,0:15:21.581
We indeed don't yet know what is[br]the true dark Universe.

0:15:21.751,0:15:26.092
There is a so dark Universe that[br]light cannot be released,

0:15:27.014,0:15:30.332
not only released light[br]doesn't go through atmosphere.

0:15:31.322,0:15:36.072
It is a Universe substantially invisible[br]for any light type.

0:15:37.100,0:15:40.452
Then we recently learned[br]over the past 50 years,

0:15:40.902,0:15:44.192
many things about the Universe.

0:15:44.502,0:15:48.572
We know it is flat, homogeneous,[br]isotropic, made of radiation,

0:15:48.892,0:15:52.370
matter, protons, neutrons,[br]as we are,

0:15:52.593,0:15:55.403
but we knows that is 4% only of the whole.

0:15:55.783,0:15:57.841
It exists a component, called dark matter,

0:15:58.161,0:16:01.102
that we know is about 23%,

0:16:01.502,0:16:04.372
six more times plenteous than usual matter

0:16:04.534,0:16:08.163
and it is in this room, it goes across us,[br]but we cannot see it.

0:16:08.903,0:16:12.514
Not only, we understood that there is[br]another 73%,

0:16:12.834,0:16:16.043
which is vacuum-hidden energy,[br]absolutely unknown

0:16:16.313,0:16:18.632
beside that it exists.

0:16:18.822,0:16:21.122
Among other things, primeval anti-matter

0:16:21.192,0:16:23.092
that symbolizes Big Bang

0:16:23.143,0:16:25.572
has gone away and we don't know[br]where it has been.

0:16:25.960,0:16:28.623
So we learned to look at[br]all the Universe colours

0:16:28.903,0:16:31.100
but while we are doing so,

0:16:31.232,0:16:34.596
we discovered that about 95%[br]of the Universe,

0:16:34.986,0:16:38.593
which is literally here, but invisible,

0:16:38.876,0:16:41.043
using all the techniques we invented

0:16:41.419,0:16:43.372
over the past 50 years,

0:16:43.702,0:16:46.270
So we know that we don't know,

0:16:46.420,0:16:48.869
we never have been[br]so consciously ignorant

0:16:49.196,0:16:52.074
about nature.

0:16:52.709,0:16:56.751
So, after a century[br]of extraordinary growth

0:16:57.433,0:16:59.964
after a literally exploding technology

0:17:00.274,0:17:02.792
that opened us all the Universe colours,

0:17:03.002,0:17:05.363
we reached a new board, a new border,

0:17:05.563,0:17:09.643
we know that 95% of what is around us[br]should still be discovered.

0:17:10.584,0:17:13.709
So we are on the new millennium[br]thresholds

0:17:14.594,0:17:16.955
when we have still to discover most things

0:17:17.098,0:17:20.156
which are around us.

0:17:20.459,0:17:24.792
So my meaning for this TEDx Talk is,

0:17:25.751,0:17:31.210
"AAA. We know that 95% of Universe[br]is invisible at all.

0:17:31.709,0:17:34.668
Looking for ideas to understand[br]what is made of."

0:17:34.959,0:17:36.877
Thank you.

0:17:37.667,0:17:40.001
(Applause)